High Power LOP Cruise

[201er]

Do any of you cruise (or climb) at over 75% LOP? What's your speed, fuel flow, deg LOP, and temps?

[jetdriven]

I occasionally run it up to 11.2 GPH LOP, thats 85% power LOP. It only adds about 3 knots (to about 155-157)  to the low altitude cruise. It eats up the efficency, instead of 153 TAS and 15.3 NMPG, its more like 156 TAS and 14 NMPG.

 

On a cool day, its 320-330 CHT.  On a hot day, 360 or so.  I dont know the precise degrees LOP, but its around 75.

[garytex]

I'll sometimes climb at 9.3 gph, 25" MP, 2600 rpm which is 69%, 130mph, 500 fpm 370df CHT.  8.7 GPH yields cooler CHTs.  Both are kind of easygoing cruse climbs. 

[KSMooniac]

I concur with Byron, but am rarely low enough in cruise to generate those kinds of numbers.  I did use a power setting like that to break-in after cylinder work, and it did great at high power and relatively low CHT.  Yesterday I flew low (for me) at 4500' running 10.5 GPH LOP to stay out of higher headwinds.

[201er]

I occasionally run it up to 11.2 GPH LOP, thats 85% power LOP. It only adds about 3 knots (to about 155-157)  to the low altitude cruise. It eats up the efficency, instead of 153 TAS and 15.3 NMPG, its more like 156 TAS and 14 NMPG.

 

On a cool day, its 320-330 CHT.  On a hot day, 360 or so.  I dont know the precise degrees LOP, but its around 75.

 

That's all you get for spending that much more fuel? 1.5GPH extra for 3-5 knots!? Then again, going ROP on 11.2GPH, you probably wouldn't break 150knots...

[M016576]

<blockquote class='ipsBlockquote'data-author="201er" data-cid="85861" data-time="1357253682"><p>

That's all you get for spending that much more fuel? 1.5GPH extra for 3-5 knots!? Then again, going ROP on 11.2GPH, you probably wouldn't break 150knots...</p></blockquote>

Extend that logic... 1.5 gph x 3 = 4.5 gph, 5kts x 3 = 15kts..

Hmm, what burns 14.5gph at 175ktas cruise....

I love my J: that's TRUE mooney efficiency!!!

[aaronk25]

After take off let's say 1000ft agl I pull the red knob until my fuel flow goes from 17gph to 10.4-10.8. You will feel a slight power loss but not much. Prop and throttle stay forward for the time being.

After 3k feet or so ill pull the prop back to 2600 rpm as the motor is more efficient and when lean of peak you don't lose as much power reducing rpm as you would if your rich of peak. I might even ricen a bit to bring the fuel back up to same flow as when at higher rpm setting.

One thing to note is the heads are about 10-20 degrees cooler with trail flaps high power lop than they are ROP with full flaps!!!!!!!!

If your at 4k full throttle 10.5 gph just a few degrees lean of peak and you cht start to get warmer than 380 just note your current fuel flow at the current power setting and then increase your rpms 100 but use your mixture control to bring your fuel flow back down to your previous fuel flow and the cht will come down because there is less internal pressure and your spreading the same amount of energy (fuel) out over more combustion cycles. Rop is opposite.

I wish I could take some people flying to demonstrate how to safely operate a engine LOP as there is so much to learn.

Aaron

[harrispa]

Hmm, what burns 14.5gph at 175ktas cruise

 

A M20R or M20S will do better than that.

Paul

[aaronk25]

A cirrus I'm president of our flying club and we have one. Sure thought it would be better than 15gph at 175kts and that's lop.......

Couldn't talk the club into a mooney or that's the way is of had it. A ovation would have to do 185 or better on same gas wouldn't it?

[carusoam]

Cross sectional area of the Ovation is less than it's competitors and shares the same N/A engine....

At 15 gph and 175 kts, I'm ROP at 11,500’.

At 12 gph and 165 kts, I'm LOP at 11,500’.

Just sayin' Ovations and Screemin' eagles are cooler than the other guys...

-a-